How The Zebra Got His Stripes is not, tragically, one of Rudyard Kipling's Just-so stories – although it feels like ought to be, alongside How The Camel Got His Hump, the whale his throat and the rhinoceros his skin.

A new scientific review has attempted to answer that seemingly simple question, along with the reasons behind the colouration of a whole monochrome menagerie, from pandas to ring-tailed lemurs. Less poetic than Kipling it may be, but the conclusion, from Dr Tim Caro at the University of California, Davis, is that in many cases scientists know very little for sure about why animals are coloured the way they are. The field is still hotly debated.

It may be thought that such extremely conspicuous markings as those of the zebra would be a great danger in a country abounding with lions, leopards and other beast of prey; but it is not so… It is in the evening, or on moonlight nights, when they go to drink, that they are chiefly exposed to attack… in twilight they are not at all conspicuous, the stripes of white and black so merging together into a gray tint that it is very difficult to see them at a little distance. Wallace, Darwinism

The zebra is conspicuously striped, and stripes on the open plains of South Africa cannot afford any protection. Burchell in describing a herd says, "their sleek ribs glistened in the sun, and the brightness and regularity of their striped coats presented a picture of extraordinary beauty." Darwin, Descent of Man

The mystery remains unsolved. Scientists have suggested everything from the stripes setting up cooling convection currents around the body to deterring tsetse flies, but no one has the definitive answer.

As Caro points out in his review in the Philosophical Transactions of the Royal Society, there is no one explanation for why black and white animals look the way they do. Horizontal black and white bands on, for example skunks and stink badgers are probably a text-book example of warning colouration (or aposematism). As Caro writes:

Attackers are warned first by a sudden erection of a white tail, then a handstand and possibly bipedal advance, that a jet of foul smelling fluid could be accurately ejected at them from anal glands.

Black and white face masks, sported for example by the raccoon dog and black-footed ferret, may also serve similar warning functions. But Caro believes that in other species it may serve a signalling function to other members of the same species. The iconic eye-spots on the giant panda and other species are anti-glare devices, he suggests. Without them, the white of their face would reflect light into their eyes, making it more difficult to see.

The panda's large blocks of black and white on its body (along with other species such as the tapir and giant tree rat) may also serve to disrupt the outline of the body so making it harder to spot. For the panda, though, this explanation seems a little hard to swallow.

The experiments to eliminate the various explanations for any one species are hard to do well, so there is a dearth of good evidence. For the most part, scientists are still relying on just-so stories.